Outlet for conical mills



H. W. HARDINGE.

OUTLET FOR CONICAL MILLS. l

APPllCATLON FILED- OCT. 7. 192i..

1,436,877, Patented Nov. 28,1922.

. INT- f A l W INVENTOR 4 @Mbw/W ATTORNEYS Patented Nov. 28, 1922.

UNITED STATES' i 1.436,8??- PATENT OFFICE.

HARRY W. HARDIN GE, 0F NEW YORK, N. Y.,` ASSIGNOR TO HARDINGE COMPANY, INC., 0F NEW YORK, N. Y., A CORPORATION OF NEW YORK.'

oUTLErIL` ron ooNroAL MILLS.

Application filed October 7, 1921. Serial No. 505,968.

ject matter of this application relates tov grinding mills. vMore specifically it relates to grinding mills of the type now known in the art as conical mills, i. e. mills in which a conical outlet portion automatically classifies the material; being disintegrated, according to size.

A type of grinding mill heretofore invented by me comprises a rotatable drum having an inlet trunnion, or other suitable means', through which material to be disintegrated may be fed into the drum while the latter is rotating; a conical outlet portion for automatically classifying'the material according to size; and an outlet trunnion through which the fines are discharged by the rotation of the mill. One of the principal objects of the present invention is to improve the efficiency of such mills. Other objects and advantages will appear as the invention is hereinafter disclosed.'

Referring to the drawings which illustrate, what I now consider, preferred forms of the invention Fig. 1 is an elevation partly in section of one form of the invention.

Fig. 2 is a detail sectional elevation illustrating a mill in which one of the elements shown in Fig. 1 is dispensed with.

Figs. 3 and 4 are somewhat diagrammatic detail sections employed in explaining the theoryy of operation of the invention.

Referring to Fig. r1 it will be seen that I have shown a conical mill comprising a rotatable drum 10 having an inlet trunnion 21, and bearing 12 therefor; a substantially cone-shaped outlet portion 11 for the automatic classification of material according to size; an outlet opening 12 for the discharge of the material when it has been reduced to fines, i. e. particles of a predetermined size; and a bearing 13. Means. comprislng a gear wheel 15 secured to the drum, are provided.

for rotating the drum and it will be understood that balls, pebbles or other suitable grinding media (not shown) may be employed with the mill. If desirable, the drum 10 may b`e provided with suitable lining material or liners 14. Before proceeding with the description of the discharge end ofthe mill shown in Fig. 1 I shall describe outlet means hereto employed by me.

Referring to Fig. 3 (in which parts corresponding to those illustrated in Fig. 1 are designated by the same reference numerals but with subscripts it will be seen that the conical outlet portion 11'r1 discharges, through the opening 12?, into a trunnion 16a having a substantially cylindrical bore. A mill of the type illustrated in Fig. 1, but provided with the Aoutlet nmeans shown in Fig. 3, possesses marked advantages now clearly understood lby those skilled in'the art. Material to be disintegrated may be fed through the trunnion 11 into the drum 10, while the latter is rotating. It is there subjected to the disintegrating action of the grinding media. 'By virtue of the conical portion 11a the material is automatically classified according to size and the fines, i. e. particles of a predetermined size, are discharged through the outlet trunnion 16a. Though such a mill is extremely advantageous and efficient nevertheless it is susceptibletoimprovement. Thecone-sha-pedportion 11, when rotated, impels the fines outwardly. The trunnionV 16a, being cylindrical, exerts no such force so that a retardation of the flow' of fines occurs in such a trunnion. It is important that the fines be discharged from millsof the type described quickly and as soon as possible after they have been reduced to predetermined size. Fines within the mill decrease the efliciency not only because they constitute dead weight and energy is-wasted in rotating them, but also because they cushion the impact of the grinding media upon the larger particles. In accordance'with the present invention I provide means for accelerating the discharge of fines. `One form of such means is somewhat diagrammatically illustrated iny Fig. 4 and may be explained as follows.

The conical outlet portion 11b of the mill extends into the trunnion 16" and is there joined' by the smaller end of a diverging spoutmember 17b which also extends into. said trunnion and is open at its larger end. It will be noted that the members 11b and 17b form a relatively convergent-divergent outlet opening for the mill, the throat 12h being surrounded by the trunnion 16". In operation, the material is ground Within the mill and automatically classified according to size in the'outlet portion 11b, The lines pass through the throat 12b and then drop automatically and quicklyl by gravity, down the inclined Wall of the spout 17h. The efficiency of this type of mill is thereby made a maximum. A

Returning now to Fig. 1 it will be seen that the parts 11, 12, 13, 16 and 17 correspond to the parts 11", 12213", 16h, 1,7'J illustrated` inv Fig. 4. The spout or discharge member 17 is shown as comprising an outer portion, adapted to be attached to or removed from the mill by virtue of the boltv and flange connection illustrated, and an inner member 18, forming a continuation of said outer portion. It will also be noted that the member `18, constituting the inner end of the spout, is in the form of a liner 18.

Ifdesirable the conical outlet portion of the mill may be provided .with a cage 19 to prevent the discharge of the balls, pebbles or other grinding media, with which the mill may be provided, but to permit the discharge of fines by the action of the conical outlet. While this "cage may assume other forms I now prefer to employ one of the type illustrated with an opening 20 at or ad'acent its apex. A substantially cone shape member 19, provided with lateral slits or perforations of such size as to differentiate between grinding media and fines, is shown secured at its base to the apex portion of the conical outlet portion 11. The operation of the improved mill illustrated in Fig. 1 may novv be summarized as follows.

The gear Wheel is rotated to rotate the mill and material is fed intoi the mill through the inlet trunnion 21. The material Within the mill is subjected to disintegrating action and as it becomes reduced to predetermined size automatically passes through the throat 12 Within the trunnion 16. If the cage '19 is employed the fines enter the same and drop through the lopenings thereof; the grinding media being retained although the mill is being forced. The fines, upon lea-ving the cage 19 enter the discharge spout 17 and y rapidly dro-p by gravity through the latter.

In accordance with the provisions of the patent statutes I have disclosed What I no-W consider a preferred form of the invention.

vIt will be understood that the structure illustrated may be modiiedin various respects the corresponding liner 18 shown in Fig. 1.

Other modifications Within the scope of the appended claims Will occur to those skilled in the art and, to avoidsurplusage, I have omitted specific. tions.

What I claim is l 1. In combination, a conical grinding mill having a4 convergent-divergent outlet opening for automatically classifying material according to size and automatically discharging the same upon rotation of the mill, a cage Within said outlet opening for preventing the discharge of grinding media, and a trunnion bearing for said mill surrounding the throat of said convergent-divergent outlet opening.

2. A conical grinding mill comprising in combination, a. trunnion and bearing therefor, a rotatable drum provided with substantially cone-shaped outlet portion provided at its apex With a cage for preventing the discharge of grinding media, and a diverging spout extending into said trunnion and into which said drum discharges.

3. A conical grinding mill comprising 'in combination, 'a bearing, a. rotatable drum having a. substantially cone-shaped outlet portion which extends into said bearing, and a diverging, discharge spout extending into the opposite end of said bearing for receiving the discharge of said outlet portion.

4. A conical grinding mill comprising inv combination, a rotatable drum-having Aa subst-antially cone-shaped outlet portion provided at its. apex with a substantially coneshaped cage for preventing the discharge of grinding media.

5. A conical grinding mill comprising in combination, a rotatable drum having a substantially cone-shaped outlet portion provided at its apex with a substantially coneshaped cage for preventing the discharge of grinding media, and a diverging discharge spout surrounding said cage to receive the discharge of fines therefrom.

' In testimony whereof I hereto afiix my signature.

HARRY W. HARDINGE.

disclosure of such modifica- 

